Gun rammer



L. A. TROFIMOV April 18, 1944.

GUN RAMMER Filed Dec. 4, 1942 2 Sheets-Sheet l Apni 8, 19. 1.. A. TROFIMOV 2,345,877

GUN HAMMER I Filed Dec. 4, 1942 2 Sheets-Sheet 2 atenie NT OFFICE GUN Lev A. Troflmov. Willoughby, Ohio Application December 4, 1942, Serial No. 467,825

3 Claims.

This invention relates to power apparatus for reciprocating the rammer of a gun to successively charge the projectile and the powder into the breech of the gun.

Such power operated rammers are well known. Heretofore hydraulic power has been considered as the most practicable for this purpose, notwithstanding that it has certain inherent disadvantages. Electric motor power has been proposed to overcome these disadvantages of hydraulic power, but the reclprocatory character of the load, that is to say the driving of t e. reciprocatory rammer, has introduced problems in the application of electric power that have not been satisfactorily solved. Furthermore, it is rec- ,ognized that alternating current motor power would be preferable to direct current motor power, but the problem of applying electric motor power to operate the rammer has heretofore been found to be even more ,difiicult of solution with alternating than with direct current.

It follows that a complete solution of the problem calls for the application of alternating current motor power to the reciprocation of the gun rammer, and in the following is described such a solution to this problem.

It is therefore the primary object of this invention to provide a power apparatus for reciprocating a gun rammer in the forward and reverse directions, and with difierent lengths of stroke of the rammer to suitably and successively position the projectile and one or more charges of powder in the breech of the gun, utilizing electric motor power therefor.

Another object is to provide such a power apparatus as that referred to above in which the electric motor power may be that derived from alternating current.

Another object is to provide such a power apparatus having improved means forcontrolling the movements of the reciprocatory rammer.

Other objects will be apparent to those skilled in the art to which my invention appertains.

My invention is fully disclosed in the following description taken in connection with the accompanying drawings in which:

Fig.1 is a view, somewhat diagrammatic, illusin association with the electric circuits which they control:

Figs. 3, 4, 5, and 6 illustrate diagrammatically a gun rammer operated by the apparatus and system of Figs. 1 and 2, and illustrating different positions and lengths of stroke of the rammer as it successively propels the projectile and two charges of powder into the breech of the gun;

Fig. 7 is a view illustrating a modification of the control system of Fig. 2.

Fig. 8 is a view illustrating a means for adjusting cam devices of Figs. 1 and 2.

Referring first to Figs. 3, 4, 5, and 6 of the drawings, I have illustrated diagrammatically at i the breech of the gun to be loaded. At 2 is a pan or shelf upon which first the projectile and then the powder is deposited preparatory to being charged into the gun. At 8 is a horizontally reciprocable rammer having a rammer head i.

In each of the Figures 3 to 6, the rammer head A is illustrated in solid line in its retracted position. In Figs. 3, 4, and 5, the rammer head is shown at AA, 43 and C in its forward reciprocated position to which it is moved by successively shorter forward strokes. 0n the first forward stroke, the rammer head 6 moves a projectlle 5, which has been laid upon the pan 2, from its solid line or starting position to its final position indicated in dotted line in the gun; and in Fig. 4 a first charge of powder 6, which has been laid on the pan 2, is reciprocated forwardly to the dotte line position rearwardly 0f the proiectile in the gun; and in Fig. 5 a second charge of powder 1, which has been laid on the pan 2, is reciprocated forwardly to the dotted line position in the gun rearwardly of the first charge 8; and in Fig. 6, which illustrates the projectile and both charges of powder in the gun, the rammer head 5 has been retracted, and the gun breech may now be closed and the gun fired in the usual trating an electric power apparatus for operating I manner by means not shown.

It is therefore seen to be convenient to always to retract the rammer head 4- to the same position, but to project it forwardly over successively decreasing distances.

The rammer proper, 3, which reciprocates the rammer head 4, may be variously constructed. In one acceptable and practicable form, the rammer proper is in the form of a chain, and, upon retraction thereof, the chain winds or bends into a housing whereby the overall length of the rammer may be kept down to the minimum; but inasmuch as the construction of the rammer proper constitutes no essential part of the present in- 2 I vention, and in order to'simplify the and description, the rammer has been illustrated as inthefomiofarack.r-eciprocaiedlvyforward' and reverse rotation of a pinion I meshed therewith, and driven by a shaft I. If the chain-form rammer were employed. the pinion I, or a sprocket connected to the shaft I, would reciprocate the chain.

The apparatus for thus rotating the shaft [in the forward and reverse directions and for carryins out the other features of movement of the rammer head 4 above referred to, will now be described in connection with Figs. 1 and 2, wherewhich rotatively supports pinions lit-l4 meshed with'diflerential gear elements I! and II.

The differential gear it drives the shaft I preferably through a friction clutch I] which clutch as is well known will slip if the torque necessary to rotate the shaft I and pinion I should exceed a predetermined amount.

The differential gear 15 is connected by a shaft II to the rotor of a squirrel cage induction motor II, having as indicated conventionally, three sets of stator field windings. or a stator field windin that can be connected to supply mains to provide in eflect three sets of windings. whereby its rotor may have three synchronous speeds at which it tends to run. The above mentioned motor II has a single speed at which it tends to run.

The three different speeds of the motor l9 and the speed of the motor II may be variably chosen, and the gear ratio between the pinion H and the spider II may be variously chosen. "As a concrete illustration and for purposes of description herein, the motor III has a synchronous speed of 1,800 revolutions per minute; and the gear ratio is oneto-three; whereby the spider II is driven at 600 revolutions per minute; and the three speeds of the motor II are respectively 600, 1,200, and 1,800 revolutions per minute. as indicated in the drawing. From this it will be apparent to those skilled in the art, that due to the characteristics of the differential gearing illustrated and described, when the motor II and the shaft II and gear 15 are running at 1,200 revolutions per minute, the differential gear I I and shaft I will remain at rest; and that when the motor II is running at 600 revolutions per minute, the shaft I will rotate at 600 revolutions per minute in, say, the forward direction; and that when the motor II is running at 1,800 revolutions per minute, the shaft I will rotate at 600 revolutions per minute in the reverse direction. e

The motor II runs continuously, andnormally the motor II runs at 1,200 revolutions per minute to hold the shaft I and its rammer driving pinion I at rest to hold the rammer at rest. To reciprocate the rammer forwardly, the motor II is driven at 600 revolutions per minute; and to retract the rammer the motor II is rotated at 1,800 revolutions per minute.

The supply of electric power to the motors II and i9 and the control of the power for the purposes just described, is preferably provided by the system of connections shown in Three phase alternating current is supplied by mains 20, 2!, and 22. In the line of the mains is a threepole electro-magnetic contactor shown generally at II. the winding of which is energized across the mains :l-II under the control of a push button or other operator's contactor It. The motor II receives current directly from the supply mains when the contactor II is closed. The three sets of windings of the motor II are supplied with alternating current from the mains,

upon the closure of magnetic contactors shown generally at II, II, and 21. A manually operable master switch is shown at II and comprises an arm II which may be rocked clockwise or counterclockwise as viewed in the drawing by a handle II which is normally held in an intermediate position by springs Il-Il and in the clockwisedirection it engages and bridges contacts I2 and II, and in the other direction engages and bridges contacts I4 and II. A selector switch is shown generally at II and comprises a contact arm I! rotatable by a handle II to selectively engage one or the other of three contacts II, II or II. At 42 is shown generally a set of four limit switch devices comprisi 1g normally closed switches II, II and II, and a normally open switch II, and rotary cams or like devices II, II, II, or II for operating the said switches. These switch operating cam devices are shown as rotatable in unison by a shaft Ii. As shown in Fig. 1, where these parts are reproduced this shaft is driven by the load shaft I through a pinion I: on the shaft I meshed with a gear II which transmits its rotary movement through a gear ratio reduction unit It to the shaft 5|.

" mally closed contacts II and normally open con-' At II is an electro-magnetic relay having nortacts I1.

. Other parts of Fig. 2 and circuit connections thereof not described above will now be described i connection with a description of the operatic as a whole, referring to Figs. 1 and 2.

Upon closing the operator's contactor II, the main line contactor it closes, and current from the supply mains 20, II and 22 goes directly by wires II, II, and II to the motor l0, energizing it and bringing it up in its speed of 1,800 revolutions per minute.

A branch system of three phase wires II, II, V and II connected to the wires II, II, and II is thereby energized. Current flows from the wire II by a control circuit wire II, through the windin: II of the magnetic contactor 28 and by a wire 86 through the closed contacts so of the relay n and by a return wire 61 to the wire I2, energizing the winding II and closing the contactor II; and thereupon three phase current flows through I! the contacts of this contactor to one of the windings of the motor II, namely, the winding which operates it at 1,200 revolutions per minute, as in- -dicated by the use at the motor II of the refer? ence character 1, 00, andthls brings the motor II up to its speed of 1,200 revolutions per minute;

and as will be understood from the foregoing, the load shaft I now remains at rest notwithstan that both motors are running. I

To operate the load shaft I in the forward direction for the purpose of positioning the projectile in the gun as was heretofore described, it

y will be assumed that the selector switch II has its contact I! on the contact II. The master switch II is now operated to move the arm II clockwise and bridge the contacts I2-I3; whereupon current flows by a control wire II from the wire 63 to the arm 29, thence to the contact I2, by a wire 69 to the arm II, to the contact II, by a wire 10, to and through the limit switch 45 and by a wire 1| through the winding 12 of the relay st and thence to the return wire t1, thereby operating the relay 55 to open the contacts 56 and close the contacts Opening of the contacts 53 m described, deenergizes the contactor 2s and cuts oil current from the motor iii; but operation of the relay 63 also immediately closes the contacts 51, and thereupon current flows at the master switch, as described, to the contact 33 and thence by a wire it through the winding M of the contactor 26 and by a wire through the now closed contacts 51 of the relay 55 and to the wire 61 and so on as before, operating the contactor 28 ,and connecting the supp wires ti, 62, and 63 through th contactor 26 to the winding of the motor it which operates it at 600 revolutions per minute as indicated.

This as described hereinbefore causes the load shaft 9 to rotate in the forward direction to project the rammer forwardly to position the projectile in the gun.

Rotation of the shaft 9 rotates the cam switch shaft at as described. When the shaft begins to rotate, the cam device 5Q, after a email angle of rotation, allows the switch to to close, but this at the present moment effects no change.

By the time the shaft 9 has rotated a sumcient number of revolution to efiect the projectile positioning rammer stroke identified with Fig. 3, the cam shaft 5! has been rotated by the re uction gearing described, sufficiently to cause the cam device 69 to open the cam switch t5, the cam shaft ti and the cam device as being considered as rotating in the direction of the solid linearrow associated therewith in Fig. 2.

Opening of the switch d5 die-energizes the relay 5% causing it to restore and open the contacts 51 and close the contacts 56 which, as now will be understood from the foregoing description, causes .the contactor it to open and the contactor to close again, restoring the motor IQ to its 1,200 revolution per minute speed and bringing the shaft 9 to rest at the end of the rammer stroke.

As was described in connection with Figs. 3, 4. and 5, the successive forward rammer strokes were respectively long, intermediate and short. The cam device til accordinghr will be set to operate its switch 65 after a relatively great part of a revolution of the shaft 5i, and as will presently appear, the cam devices t8 and Al are respectively set to operate their switches M and 63 after intermediate and short portions respectively of a revolution of the shaft 59.

To retract the rammer the master switch 28 is now operated to move the arm 29 in the counterclockwise direction to bridge the contacts 86, and thereupon current flows as before by the wire 68 to the arm 29 and to the contact and thence by a wire it through the now closed limit switch 56 and by the wire H to again operate the relay and close the contacts 51 and open the contacts 55; and current also flows from the master switch arm 29 to the contact 34 and thence by a wire Tl through the winding 18 of the contactor 21 and by a wire 19 to the above described wire I5 and thence through the now closed contacts 57 of the relay and thence by the wire 61 and so on as before, thereby closing the contactor 21 and supplying three phase current from the wires til, 82, and 83 to the motor l9 to operate it at its speed of 1,800 revolution per minute, as indicated.

This, as described above, causes the load shaft s to reverse its direction of rotation and retract the plunger. Rotation of the shaft 9 in the reverse direction reverses the direction of the cam shaft 5| and causes the cam device 58 to rotate in the direction indicated by the dotted line arrow, and to open the limit switch 46 by the time the rammer has been retracted o its original position, whereupon the relay 55 again restores, causing the motor l9, as will now be clear, to operate at its speed of 1,200 revolutions per minute and bring the shaft 9 to rest again. This brings all of the parts back to the condition at which the operation started, the rammer having moved the projectile into the gun and retracted to its starting position.

To perform the ramming operation indicated in Fig. 4, the operator moves the selector switch 36 by the handle 38 to engage the contact 31 with the contact 40; and then moves the master witch arm 29 to bridge the contacts 32-88. Current now flows from the contact 32, as will be apparent, through the limit switches 46 and 5 to operate the relay B5. The operation is now the same as on the first stroke of the rammer, the motor I9 being caused to rotate at 600 revolutions per minute, but in this case, the cam device 18 opens the limit switch M earlier in the stroke of the rammer and restores the motor is to its 1,200 revolutions per minute earlier and stops the rammer at a shorter stroke. Again, moving the master switch arm 29 counter-clockwise causes the motor l9 to operate at 1,800 revolutions per minute .and reverse the rammer, and the limit switch 66 upon being restored, again causes the rammer to come to rest.

For the third stroke of the rammer, identified with Fig. 5, the selector switch 36 is moved to engage the contact 81 with the contact 4!; and then when the master switch 28 is moved clock wise, current from the contact 32 flow from the contact M and through the limit switches 43, M and 45, again operating the relay 55 and causing the motor it to rotate at 600 revolutions per minute; and the cam device 81 opens the limit switch it at a still earlier point in the rammer stroke performing the ramming operation of Fig. 5. And again, when the master switch 28 is moved counter-clockwise, the motor I9 is caused to run at 1,800 revolution per minute and reverse the load shaft and the cam shaft and retract the rammer, at the end of which movement the limit switch 68 again brings the apparatus to rest.

As will be seen from the foregoing, the amount of retraction of the rammer is always determined by only one limit switch, 46, and the rammer therefore always retracts to the same position.

It will be observed that to cause the rammer to move forward the relay 55 is first raised and then the contactor 26 is closed. In some cases, it may be desirable to give a forward movement to the rammer independently of the limit switches, such for example as a small or inching movement. When this is desired, an operators switch or push button may be moved to momentarily, or repeatedly, close its contacts Bl.

Current then will flow from the supply main 63 through the contacts 8| and by a wire 82 to the wire H to effect raising of the relay, and current will also flow through the contacts 8! and by a wire 83 to the winding It and through it to the wire 15 and so on, effecting momentary or repeated closing of the contactor 26.

In the foregoing description, the selector switch 36 is arranged to be moved from one position to the other by hand.

In the modification shown in Fig. 7, this may be accomplished automatically. A ratchet wheel at i connected to the contact 31. A pawl arm 85 is pivoted at the center of the ratchet wheel at and a pawl 06 on the arm 85 engages the teeth of the ratchet. A rod 87 is pivotally connected to the arm 85. A spring 88 connected to one end of the rod 81 tends to rock the arm 85 clockwise to turn the ratchet wheel and move the contacts 31 from one position to another. An electromagnet comprising a winding 89, and a plunger 50 connected to the rod 81 tends to rotate the arm 85 counter-clockwise to tension the spring 88. Limit stops 9i and 92 are adjustable to predetermine the angular stroke of the arm 85.

The limit switch 46 rotated by the cam device 50 has another switch 93 associated therewith which opens and closes concurrently with the switch M. A circuit from one of the supply mains 62 through the switch as and through the winding 89 to another supply main E3 is provided.

In the operation of the apparatus of Fig. '7 above described in connection with Fig. 2, when the rammer starts forward, the limit switch it closes. In Fig. 7, this also closes the switch 33 and energizes the winding 89 and raises the plunger 90 and rod 81 and tensions the spring 85. When the rammer has made its forward stroke and has retracted to its original position. the limit switch #36 opens; and in the arrangement of Fig. 7 this also opens the switch 93 deenergizing the winding 89 and allowing the spring 88 to ratchet the contact 31 around to its next successive position.

Thus by the arrangement of Fig. 7, each time that the rammer is retracted, the selector switch is automatically set to a new position for the next forward stroke of the rammer.

The cam devices M to 50 may be of any suitable construction or of known commercial construction; and may be adjustable to adjust the times at which they operate their associated switches to determine the extent of the several strokes of the rammer. A diagrammatic showing of adjustment is given in Fig. 8, wherein the set screw 96 may be loosened and the body as of the cam device rotated on the shaft hi to adjustably position it and the set screw then tightened.

There are advantages and improvements in my invention which are not obvious from the foregoing description, as follows.

It will be observed that the motor i9 begins to move the rammer in the forward direction at the instant that its speed begins to decrease from a 1 200 to a 600 revolutions-per-minute motor. In order that the rammer may be moved forwardly without delay and be quick-acting as is known to be desirable, the motor I9 should be slowed down to its 600 revolutions per minute as quickly as possible, and there is means inherent in the invention for producing this action. When the synchronous speed of the motor i9, that is, the speed of its rotating magnetic field, is changed from 1.200 to 600 revolutions per minute, the rotor is at that instant still rotating at 1,200 revolutions per minute, which is twice the new synchronous speed. The motor then as is well known will operate as an induction generator, developing electrical load and delivering it back to supply mains and this electrical generator load quickly slows down the rotor by what may be called dynamic braking. Furthermore, and additive thereto, the kinetic energy of the motor rotor upon slowing down from the higher speed assess"? is partly absorbed by theload to start and accelerate it. Thus very quick, it not instantaneous, starting and accelerating oi the rammer occurs and without the-necessity of correspondingly accelerating the motor itself which has been necessary in prior electrical systems for this purpose.

Again, at the end of the forward rammer stroke the motor I9 is changed from a 600 to a 1,200 revolutions-per-minute motor to stop the forward movement of the rammer, and it is likewise desirable that this change of speed shall occur as quickly as possible; and again means is inherent in the invention to accomplish this end. The instant that the rotating magnetic field oi the rotor is changed to 1,200 revolutions per min ute, the rotor is still rotating at 600 revolutions per minute; and thetorque developed by the high speed rotating field is very much greater, approximately twice that which was developed when the magnetic field was rotating 600 revolutions per minute, so that, a very great or what may be called excessive torque is applied to the rotor at its 600 revolutions pervminute speed, to quickly bring it up to the 1,200 revolutions per minute speed.

When the rammer is started in the reverse direction the motor speed must be changed from 1,200 to 1,800 revolutions per minute and again this is brought about very quickly because of the fact that with the rotor going at 1,200 revolutions per minute-and the speed of the rotating magnetic field instantaneously changed to 1,800 revolutions per minute, the very great or excessive torque thereby applied to the rotor very quickly brings it up to the new speed; and this is further facilitated by the fact that at this time there is no load on the motor except the idle returning rammer.

At the end of the returning stroke of the rammer, the motor speed changes from 1,800 revolutions per minute to 1,200 revolutions per minwho and here again, when the connections to the stator are changed. the rotor is rotating above the new synchronous speed and again acts as an induction generator developing electrical load which very quickly reduces the speed of the rotor.

Thus the speed of the motor 19 is automatically and inherently quickly changed in the operation of the apparatus as described and this, coupled with the fact that both motors run continuously and do not have to be stopped and started and reversed, enables them to run at very high eficiency; and for a given output horsepower makes possible the use of smaller motors than would otherwise be necessary, and avoids the necessity of auxiliary apparatus to accelerate or decelerate the motors or either of them to effect the changes of speed and direction of the load.

My invention is not limited to the exact details of construction illustrated and described nor to the exact arrangement of the electrical connection thereof. Changes and modifications other than those described above may be made within the scope and spirit of my invention without sacrificing its advantages; comprehends all such changes and modifications which come within the scope of the appended claims.

I claim:

1. In a power operated gun rammer apparatus, a reciprocatory rammer: a power transmission mechanism; a constant speed electric motor and a variable speed electric motor, connected to the and my invention prising means coordinated with themovement 1 of the rammer to effect changes of speed of the variable speed motor after a predetermined extent of movements of the rammer in the forward and reverse directions.

2. In a power operated gun rammer apparatus, 15 i a reciprocatory rammer; a power transmission mechanism; a constant speed electric motor and a variable speed electric motor, connected to the transmission; a power take-ofi from the transmission mechanism connected to the ramm'er; 20

the transmission mechanism comprising means to effect forward and reverse movements of the rammer and to bring it to rest, responsive respectively to diflerent speeds of the variable speed motor; a source of current for the motors; a 2

control system controlling the current to control the speed of the variable speed motor, and comprising means coordinated with movement of the rammer to effect changes of speed of the variable speed motor after a predetermined ex- 30 tent of movements of the rammer in the forward and reverse directions; and operable means to variably predetermine the extent of forward movements.

3. In a power operated gun rammer apparatus, a reciprocatory rammer element; a differential gearing comprising three elements, namely: a rotary spider element rotatably supporting a pinion and two rotary differential gear elements meshed with the pinion; a constantly running electric motor drivingly connected to one element of the gearing and rotating it at constant speed; a power take-off from a second element of the gearing for reciprocating the rammer element; a variable speed electric motor drivingly connected to the third element of the gearing; a source of current and control means for causing the variable speed motor to run at different respectivespeeds at which the said power takeoff remains at-rest, and at which the power takeoff, reciprocates the rammer element in the forward direction, and at which the power take-oft reciprocates the rammer element in ,the reverse direction, respectively; stop means operable by the power take-off and controlling the control 5 means to limit the movement of the rammer element in the forward and reverse directionsof reciprocation: and selector means controlling the stop means to selectively predetermine the extent of successive forward reciprocations.

' LEV A. TROFIMOV. 

